Magnetically operated switching apparatus



Nov. 18, 1969 D. F. WILKES MAGNETICALLY OPERATED SWITCHIN G APPARATUS 2 SheetsSheet 1 Filed March 29. 1968 INVENTOR DONALD F. WILKES Nov. 18, 1969 o. F. WILKES 3,479,524

MAGNETICALLY OPERATED SWITCHING APPARATUS Filed March 29, 1968 2 Sheets-Sheet 2 United States Patent Ofiice 3,479,624 MAGNETICALLY OPERATED SWITCHING APPARATUS Donald F. Wilkes, Albuquerque, N. Mex., assignor to Rolamite Technology, Incorporated, San Francisco, Calif., a corporation of California Filed Mar. 29, 1968, Ser. No. 717,113 Int. Cl. H01h 5/02 US. Cl. 335-188 11 Claims ABSTRACT OF THE DISCLOSURE A relay having elongated pole elements between which is positioned a tiltable armature connected to a resilient snapper element having a pair of bi-stable segments. Tilting movements of the armature in response to coil energization cause the snapper segments to snap back and forth between their stable positions to make and break electrical contact with stationary contact elements.

CROSS REFERENCES TO RELATED APPLICATIONS Two patent applications of Donald F. Wilkes entitled respectively Snap Action Apparatus and Electrical Contact Making and Breaking Apparatus are being filed concurrently herewith. These applications disclose related subject matter, and the disclosures thereof are incorporated herein by reference.

BACKGROUND OF THE INVENTION This invention relates to magnetically operable switching apparatus in which an armature is caused to move in response to magnetic forces and in which movements of the armature serve to actuate bi-stable snap-acting elements that carry out electrical switching functions. The invention is particularly suitable for use in miniature relay constructions.

In the design of relays and other types of magnetically operable switching apparatus, much attention has been given heretofore to the problem of maximizing magnetic flux utilization. This problem becomes particularly important in connection with small devices in which coil size must be restricted because of space limitations and/ or because of limited heat dissipating capabilities. However, the proposed solutions have been only partially suceessful, and in most of the prior art constructions the positional relationships between the movable armatures and the magnetic pole pieces have been such that the flux paths have been unnecessarily inefficient.

Difliculties also have been experienced in obtaining efiicient electrical contact making and breaking functions in these magnetically operable devices. In a typical relay construction for example, a movable contact element is held against a back contact by a spring of some sort and is moved against the action of the spring by the armature to draw it away from the back contact and bring it into engagement with a front contact upon energization of the relay coil. However, a critical analysis of the forcespace relationships inherent in such devices makes it evident that they cannot be operated to produce sharp definitive contact breaking functions unless the coils are capable of quickly generating very large magnetic forces.

Moreover, the prior art proposals are in general difficult to apply in connection with the design of small devices which must be manufactured on a mass production basis. In such applications, dimensional tolerances become exceedingly critical and irregularities in the materials from which the parts are fashioned are troublesome.

3,479,624 Patented Nov. 18, 1969 SUMMARY OF THE INVENTION The magnetically operable switching apparatus of this invention overcomes or avoids the difliculties and problems outlined above. A key feature of the new apparatus is an improved armature-movable contact assembly which, in a preferred embodiment, includes an elongated arrpature permanently magnetized along the direction of lts length and a snapper element of thin resilient material having a central opening disposed in surrounding relationship to the armture. In the assembled positions of these parts, the snapper element is elastically stressed in patterns which cause the end portions thereof protruding beyond the ends of the armature to cone out of the plane of the armature. The elastically coned end portions of-the snapper are bi-stable. Each of them may assume coned configurations extending either above or below the plane of the armature.

In the assembled apparatus, the coned snapper segments at opposite ends of the armature are caused to extend away from the plane of the armature in opposite directions. Opposing stationary reaction surfaces are located in the paths of movement of the free outer end portions of the snapper segments and serve to limit the extent of movement of these portions.

Some or all of the reaction surfaces may be electrically conductive, and the snapper element is provided with electrically conductive surface portions for cooperating with the electrically conductive reaction surfaces. In addition to providing movable contacts, the snapper element may also bear whatever circuit elements may be desired.

The armature-movable contact assembly is disposed between a pair of elongated magnetic pole pieces and mounted so as to permit tilting movements of the armature about an axis located approximately midway between the ends of the armature and midway between the pole pieces. The extent of tilting movement permitted however is limited by the presence of the opposed pole pieces. In one extreme position of the armature, its nort end will contact one of the pole pieces while its south end contacts the other of the pole pieces. In the other extreme position of the armature, an opposite relationship between its ends and the respective pole pieces will prevail.

Movement of the armature between its extreme positions under the influence of magnetic forces applied through the pole pieces will function first to increase the bearing forces between the outer end portions of the snapper segments and the reaction surfaces, and then to suddenly snap the snapper segments into the oppositely directed stable positions thereof.

This construction has many practical advantages. For example, flux utilization is optimized by the novel arrangement of the armature with respect to the pole pieces, and the snap actions achieved in the snapper end segments in response to armature movements assure effective contact making and breaking operations.

An equally important attribute of the construction is that it may be manufactured reliably on a mass production basis. The snapper element is formed from thin'sheet material which is highly uniform in its structural properties, and the outlines of the element may be established with precision through the use of photochemical processing techniques analogous to those employed in chemical milling operations and in the production of printed circuit components. Additionally, there are very few critical dimensional relationships in the entire construction so that it generally is not necessary that close tolerances be maintained in the fabrication of the components or in assembling such components.

3 BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of these and other features and advantages of the invention will be gained from a consideration of the following detailed description of certain embodiments illustrated in the accompanying drawings, in which FIGURE 1 is an elevational view, with a casing component illustrated in cross section, of a small relay embodying the principles of the invention;

FIGURE 2 is a horizontal cross-sectional view taken along line 22 in FIGURE 1;

FIGURE 3 is a plan view of a resilient snapper element suitable for use in the relay of FIGURES l and 2;

FIGURE 4 is an enlarged, transverse cross-sectional view taken along the line 44 in FIGURE 3;

FIGURE 5 is a longitudinal cross-sectional view take along the line 55 of FIGURE 6; I

FIGURE 6 is an end elevational view of the left en of the relay, with a portion of the casing being shown in cross section;

FIGURE 7 is a transverse vertical cross-sectional view generally along the line 77 in FIGURE 1;

FIGURE 8 is a plan view, similar to FIGURE 3, but illustrating an alternative snapper configuration suitable for use in relays of the type illustrated in FIGURE 1; and

FIGURE 9 is an enlarged vertical cross-sectional view taken along the line 9-9 in FIGURE 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The relay chosen for illustration in the drawings is a small device sometimes characterized in the trade as a half crystal can relay. It includes a base member 2 having contact pins 4 mounted therein and electrically insulated therefrom by suitable ceramic material 6. For reasons which will become clear hereinafter, the material from which the base 2 itself is formed, should be one which will give the base a high capacity for transmitting magnetic flux. A cover 8 of suitable non-magnetic material fits tightly over the periphery of the base 2 to provide an enclosure for the coil and switching components. If desired, hermetic seals may be provided between the cover 8 and the base 2 so as to protect the interiorly lo cated components against the deteriorating influences of environmental gases.

A bracket structure 10 of suitable non-magnetic material is attached to the upper surface of the base 2 as indicated at 12. This bracket structure 10 includes four vertically extending leg portions 14 and a horizontal platform 16 (FIGURE 7), one end portion 18 of which is disposed at a level beneath the main body of the platform as indi cated in FIGURE 5. The portion 18 is provided with laterally spaced apart reaction surfaces such as those shown at 20, and additional reaction surfaces 22 at the opposite end of the device are supported at the same level by means to be described below. In some forms of the invention, these reaction surfaces 20 and 22 will be electrically conductive and will serve as stationary contacts. Each of the downwardly facing reaction surfaces is directly above one of the contact pins 4.

An electrical coil 24 wound on a generally rectangular core form 26 is supported by the main body portion of the platform 16 at an elevation above the base 2 of the relay. Extending through the core form 26 is an elongated element 28 of a material such as soft iron, which will serve as a good conductor of magnetic flux.

The element 28 is formed from an elongated, somewhat thin, sheet. The desired thickness is achieved by folding the sheet back and forth upon itself as indicated in FIG- URE 7. This folded construction gives the element 28 ample flux-carrying capacity, but the element as a whole is relatively easy to bend.

At the left end of FIGURE 5, the element is shown as being bent downwardly as it emerges from the end of 4 the coil 24. Then, it is bent again at the level of the platform 16 and caused to extend longitudinally along the lower face of the platform 16. Spot welds, or the like, may be employed to secure the end portion of the element 28 to the platform 16.

The element 28 also is bent downwardly as it emerges from the right end of the coil 24 in FIGURE 5. This downwardly extending portion of the element 28 is connected at its lower end to the base 2 of the relay by spot welding or other appropriate techniques.

The combination of the element 28 with the base 2 e8- tablishes an extraordinarily efficient flux-conducting system. The longitudinally extending portion 30 of the element 28 on the underside of the bracket platform 16 constitutes one pole base or element, while the base 2 constitutes an opposed pole base or element disposed in generally parallel relation to the element 30. The bent configurations imparted to the element 28 make it possible for this element to join the two pole pieces together with only one joint. This joint is the one which exists between the base 2 and the lower right end portion of the element 20 in FIGURE 5. Even this joint is one which can be formed so as to minimize flux leakage because of the compliant nature of the surfaces of the element 28.

Moreover, it will be evident that, in constructions where ample space is available, the element 28 may be extended longitudinally so that the end portion from the right end of the coil will be disposed beneath and parallel to the portion 30. In such constructions there need be no joint at all.

The pole element 30, the base 2 and the downwardly facing reaction surfaces 20 and 22 define a shallow elongated switching chamber 32. Disposed in this switching chamber is a novel armature-movable contact assembly 34 carried by transversely spaced-apart central posts 36 and 38 which may be attached to the base 2 in the same fashion as the contact pins 4.

FIGURE 3 illustrates in isolation, a thin, lightweight, resilient snapper element 40 which forms an important part of the novel armature-movable contact assembly. This snapper element 40 is provided with an elongated central opening 42 having concave end edge portions 44 which define the inner ends of protruding end segments 46 and 48. The end segments 46 and 48 are joined together by longitudinally extending side strips 50 and 52.

Each of the end segments 46 and 48 has an external edge outline such as to provide the segment with a pair of protruding contact fingers. The finger portions of the segment 46 are designated 54 and 56, while the finger portions of the end segment 48 are designated 58 and 60. These finger portions constitute integral parts of the respective end segments 46 and 48, and in the illustrated arrangement, each pair of fingers functions as a mechanical unit.

The side strips 50 and 52 are provided with longitudinally extending stiffener ribs 62 at their outer margins. These stiffening ribs 62 are formed by conventional stamping techniques which serve to permanently deform the material of the snapper element 40 in the zones of the ribs.

The side strips 50 and 52 also include mounting tabs 64 and 66 extending inwardly into the central opening 42 at a mid portion of the element. These tabs 64 and 66 are, in the assembled relay, affixed to the upper ends of the mounting posts 36 and 38 in the manner indicated in FIGURE 7.

As illustrated in FIGURE 4, the snapper element 40 is a laminate, made up of a bottom layer 68 of springmetal sheet material, an insulating layer 70 of plastic material such as a polyester sheet, and a partial top surface layer 72 of electrically conductive material such as copper. The several layers 68, 70 and 72 are adhered together through sheet adhesive layers 74. It will be understood of course that the thickness of the laminate is greatly exaggerated in FIGURE 4. In one embodiment,

the overall thickness of the laminate is only 0.004 inch, and in applying the invention, it will rarely be found necessary to use snapper elements thicker than a few hundredths of an inch.

The outlines of the electrically conductive layer 72 may form patterns of considerable intricacy. Photochemical processing techniques of the type used in the manufacture of printed circuits are available for economically tailoring the final shape of the partial layer 72 in any desired manner. The particular shape illustrated in FIG- URE 3 is one which provides the upper face of the snapper 40 with electrical contact surfaces 76 at the free outer ends of the several contact fingers 54, 56, 58 and 60. The contact surfaces 76 on the fingers 56 and 60 are connected together by a portion 78 of the electrically conductive layer 72, and this portion 78 is, in turn, extended into the mounting tab 64 of the snapper 40 so that an electrical outlet connection may be made through the mounting post 36.

An armature 80 is mounted within the central opening 42 in the snapper element 40. The armature 80 preferably is permanently magnetized along the direction of its length. In the drawings, the left end portion of the armature has been designated a south magnetic pole and the right end portion has been designated a north magnetic pole for illustrative purposes.

This armature 80 includes enlarged end portions 82 and 84 connected together by an elongated center portion 86. Each of the end portions 82 and 84 is curved convexly in the areas which are to cooperate with the concavely curved end portions 44 of the edge of the central opening 42 of the snapper element 40. As shown in FIGURES 1 and 5, notches or grooves 88 are provided in the outer edges of the armature end portions 82 and 84 for receiving the curved edges 44 of the snapper.

Certain of the dimensional relationships between the armature 80 and the edges of the central opening 42 in the snapper element 40 are important. The radius of curvature of the base of each of the notches 88 is less than the radius of curvature of the curved edge 44 associated therewith. Additionally, the length of the armature, as measured from the base of one groove 88 to the base of the other groove 88 is greater than the distance between the curved edge portions 44 if measured when the snapper 40 is in a flat condition. Hence, when the snapper 40 and the armature 80 are in their assembled relation to each other, the snapper is distorted elastically. The curvatures of the edges 44 of the central opening 42 of the snapper are made to conform to the curvatures of the bases of the grooves 88 in the end portions of the armature 80, and the snapper end segments 46 and 48 cone elastically out of the plane of the central opening 42 as best shown in FIGURES 1 and 5.

The armature 80 has an overall shape such that it contacts the snapper 40 only in the zones of the curved end portions 44 of the central opening 42. The side strips 50 and 52 do not contact the armature at all and they are permitted to assume configurations which will serve to distribute the stresses in the snapper 40.

Each of the end segments 46 and 48 is bi-stable. It may assume one stable position in which its top face is convex and in which it extends downwardly at an angle from the plane of the central opening 42, or it may assume another stable position in which its top face is concave and in which it extends upwardly at an angle from the plane of the central opening 42.

In the assembled device, the two coned end segments 46 and 48 of the snapper are arranged to operate out of phase with each other in the sense that when the snapper segment 46 is coned downwardly, the snapper segment 48 will be coned upwardly and vice-versa. With this arrangement, the mid portions of the side strips 50 and 52, where the mounting tabs 64 and 66 are located, have little tendency to move as the positions of the end segments 46 and 48 are reversed. This makes it possible to use a rigid connection between the mounting posts 36 and 38 and the mounting tabs 64 and 66. The distortions which result are of minimal magnitude and are easily accommodated by the flexible nature of the material of the snapper 40. Moreover, the flexible pivot provided by the connection of the snapper mounting tabs to the upper ends of the mounting posts 36 and 38 tends to reduce the importance of locating the upper ends of the mounting posts exactly at the middle of the switching chamber. Minor positional deviations can be accommodated by the material of the snapper 40 without detracting from the performance characteristics of the device.

The upper and lower faces of the end portions 82 and 84 of the armature extend at angles to the horizontal, and, as shown in FIGURES 1 and 5, these faces may be brought into abutting relationship with the magnetic pole elements 30 and 2. This provides a closed magnetic path for the device in either extreme position of the armature 80. Flux will pass, for example, from the left end of the coil 24 through the element 28 to the pole portion thereof 30, through the armature to the base 2, and then back again to the right end of the coil through the right end portion of the element 28.

If, as in the illustrated embodiment, it is desirable that the armature have a normal position so as to provide the relay with normally closed or normally open contacts, the interior of the switching may be provided with permanent magnets for holding the armature in one of its extreme positions. In the drawings, two such magnets and 92 are shown extending along the right end portion of the base 2 with their south magnetic poles disposed in the vicinity of the north magnetic pole of the' armature 80. Similarly, permanent magnets 94 and 96 are carried by the bracket platform 16 on opposite sides of the pole element 30 and are disposed so that their north magnetic poles will be in the vicinity of the south magnetic pole of the armature.

The upper magnets 94 and 96 preferably have substantial widths as indicated in FIGURE 6, so that the upper stationary reaction surfaces 22 may be formed on or carried by the lower faces of the magnets. These reaction surfaces 22 are disposed directly above the pins 4 at the left end of the relay.

With the magnets 90, 92, 94 and 96 in place, the armature 80 will be held in the extreme position illustrated in FIGURES 1 and 5 until the coil 24 is energized to override the permanent magnets. Energization of the coil 24 serves to make the pole element 30 a south magnetic pole and to make the base 2 a north magnetic pole. The magnetic forces so generated operate first to repel the end portions 82 and 84 of the armature and tilt the armature about a transverse axis corresponding approximately to a line between the upper ends of the mounting posts 36 and 38. As the motion of the armature continues, the repulsion forces become less important and attractive forces between the pole piece 30 and the armature end portion 84, and between the base 2 and the armature end portion 82 dominate the operation of the device and serve to bring the armature into a position of rest in which the upper face of the armature end portion 84 abuts against the pole piece 30 and the lower face of the armature end portion 82 abuts against the base 2.

Of course, in many applications, it will not be necessary or desirable that the armature be biased toward a normal position. In these instances the permanent magnets 90, 92, 94 and 96 'will be removed and the reaction surfaces 22 will be formed on or carried by appropriately located elements depending from the main level of the bracket platform 16.

With the magnets 90, 92, 94 and 96 removed, the permanently magnetized armature 80 will be free to latch magnetically in either of its extreme positions when the coil 24 is deenergized. In one of its latched positions (FIGURE 5), a closed flux path will extend from the south magnetic pole to the armature, through the pole piece 30 and the core members 28, and then through the base 2 to the north magnetic pole of the armature. In the other latched position, the south magnetic pole of the armature will engage the base 2, and the closed flux path will extend in a reverse direction through the member 28.

Provisions will, of course, be made for energizing the coil 24 selectively in either direction. Upon energization of the coil 24 in the proper direction, the flux path through the core member 28 may be reversed from the direction established by the latching action, and the armature 80 may be shifted to its other extreme position.

During the tilting movement of the armature 80, the inner ends of the snapper blades 46 and 48 will be moved relative to the outer ends thereof. In explaining this action, it will be helpful to refer to particular ones of the stationary reaction surfaces defining the switching chamber in which the armature-snapper assembly is located. In FIGURE 5, a first reaction surface, located at the top of the leftmost contact pin 4 in this view, has been designated a; and a second reaction surface, located at the top of the rightmost contact pin 4 in this view, has been designated b. A third reaction surface 22 is directly above and faces the first reaction surface a. A fourth reaction surface 20 is directly above and faces the second reaction surface b. The finger portion 56 of the snapper blade 46 extends into the space between the first and third reaction surfaces, and the finger portion 60 of the snapper blade 48 extends into the space between the second and fourth reaction surfaces. Ordinarily, a similar set of four reaction surfaces would be provided for cooperation with the finger portions 54 and 58 of the blades so as to provide a balanced force pattern, but it will not be necessary here to complicate the description by specific references to these additional features.

The initial movement of the armature 80 in a counterclockwise direction in FIGURE serves to increase the bearing pressures between the finger 56 and the reaction surface a and between the finger 60 and the reaction surface 20. This results in a transverse flattening or buckling of the outer end portions of the fingers 56 and 60, and, as the motion of the armature is continued, the flattening progresses inwardly toward the armature. When the flattening effect has progressed to the inner boundaries'of the snapper blades 46 and 48, the blades will snap over to their reversely coned configurations and the fingers 56 and 60 will move quickly into engagement with the third and second reaction surfaces 22 and b respectively.

The contact fingers 54, 56, 58 and 60 cone with their corresponding end segments 46 and 48, and they will, by reason of this coning eflect, be able to transmit substantial forces. The spatial relationships within the switching chamber are such that this ability is utilized effectively. In order that substantial contact pressures may be generated when the armature 80 is in either of its extreme positions, the space between opposing upper and lower reaction surfaces is restricted to such a degree that the several contact fingers are not able to assume their fully relaxed coned configurations over their entire lengths. The outer end portion of each contact finger will bear against an adjacent reaction surface with substantial pressure and will tend to flatten somewhat.

Additional loading as between the contacts is achieved during initial movements of the armature. In fact, the contact pressure continues to increase until snapover of the snapper segments 46 and 48 occurs. This is most desirable in that good contact is maintained during contact break sequences, and little or no arcing or contact heating will occur. Moreover, the increased loading of the contacts during initial portions of the armature movements will cause the surface portion 76 of the contact fingers to scrape against the stationary contacts provided by the reaction surfaces, and the contacts will be kept clean.

Another attribute of the illustrated construction which deserves special comment is that the motions of the armature are greatly amplified in the motions of the tips of the contact fingers 54, 56, 58, 60. The armature itself tilts through a relatively small angle, but the bi-stable blades 46 and 48 snap through large angles. As a result, large air gaps between electrical contacts may be established, so as to permit the handling of high potentials, without requiring large air gaps in the magnetic circuits. In this latter connection, it will be observed that in the illustrated embodiment, the distances between the pole piece 30 and the nearest end of the armature 80, and between the base 2 and the nearest end of the armature 80, will always be very short indeed. Since the force exerted by a magnetic field varies inversely with the square of the distance, the exceedingly compact armature-pole piece arrangement provided by the invention makes it possible to minimize the size of the coil 24 without adversely affecting the performance characteristics of the device as a whole.

Even greater motion amplifications may be achieved if desired by changing the proportions of the armature 80 and the snapper element 40. The angles at which the blades 46 and 48 cone away from the plane of the armature are established by the curvatures of the armature end portions and the end edge portions 44 of the snapper element, and these angles may be the same in assemblies of different lengths. Hence, by increasing the length of the armature, one may reduce the angle of tilt of this element without causing corresponding reductions in the angles through which the blades 46 and 48 snap in response to tilting movements of the actuator.

The relative masses of the armature 80 and the snapper element 40 in the illustrated embodiment also are of interest. As explained above, the snapper element is very thin and light. However, the armature 80 may be much thicker and heavier in order that it may have completely adequate flux carrying capacity. Increases in the inertia of the armature are not ordinarily detrimental because of the small amount of armature movement required and because of the flexible coupling between the armature and the snapper element. In this latter connection, it will be observed that the inertia of the armature has little to do with the operation of the snapper blades as they move into engagement with the stationary contacts. When a blade has been snapped over its neutral position, the blade movements required to complete the snap action, take place substantially without regard to further movements of the armature. Thus, bouncing of the armature as it comes to rest in its extreme position will not ordinarily be accompanied by undesired contact bounce effects. Moreover, the extremely low masses of the snapper blades themselves minimize the inertial energy which must be dissipated in contact making sequences so that, in practice, the contact bounce problem is effectively eliminated.

Although the armature 80 chosen for illustration in the drawings is comparatively massive and although such constructions are preferred in some practical applications of the invention, it should be understood that this feature is not essential. Armatures of low mass may be used if desired. Reductions in armature mass might be indicated, for example, in applications where maximum speed of armature movement is required.

FIGURE 8 shows another form of snapper element which has been designated 4011. It is of the same configuration as the snapper element 40 shown in FIGURE 3, and corresponding reference numerals have been applied in the two views to all parts except the electrical circuit components.

As shown in FIGURE 9, the snapper 40a is formed from a laminate suitable for the production of circuit components on both faces of the snapper. This laminate includes a spring-metal central layer 98, a pair of insulating layers 100, and a pair of electrical conductive layers 102 on the outer surfaces of the component. The several layers are adhered together, as shown through adhesives 104.

With such a laminate, the circuits on the two faces of the snapper 40a may be independent or they may cooperate with each other. For purposes of illustration, FIGURE 9 shows a circuit portion 106 on the bottom face of the snapper which may be made to cooperate with a circuit portion 108 on the top face of the snapper by providing suitable means for connecting these circuit portions together at the location of mounting tab 66. Other circuit portions 110 and 112 located respectively on the top and bottom surfaces of the snapper are entirely independent of each other.

Still other variations and modifications will readily suggest themselves to persons skilled in the art. It is intended, therefore, that the foregoing detailed description of the illustrated embodiments be considered as exemplary only and that the scope of the invention be ascertained from the following claims.

What is claimed is:

1. In magnetically operable switching apparatus, an improved armature-movable contact assembly comprismg:

a magnetic armature having a longitudinal axis and a transverse axis and being tiltable about said transverse axis; and

a thin, lightweight, resilient snapper element having front and back faces at least one of which bears an electrical contact, said element being provided with a central opening therein disposed generally in surrounding relation to said armature;

said snapper element being connected to opposite longitudinal. ends of said armature at opposite ends of said central opening and being elastically stressed adjacent said opposite ends of said opening so as to cause each of the protruding end portions of said resilient element to seek a three-dimensional shape corresponding generally to the surface of a segment of a cone with said protruding end portions respectively extending away from said opening at angles on opposite sides of the plane of said opening.

2. In magnetically operable switching apparatus, the improved armature-movable contact assembly according to claim 1, wherein said armature is permanently magnetized in a direction such that said opposite longitudinal ends thereof are of opposite magnetic polarity.

3. In magnetically operable switching apparatus, the improved armature-movable contact assembly according to claim 2, wherein the mass of said armature is substantially greater than the mass of said snapper element.

4. In magnetically operable switching apparatus, the improved armature-movable contact assembly according to claim 1 in combination with first and second longitudinally elongated, spaced-apart, generally parallel, stationary pole elements disposed on opposite sides of said transverse axis in position to be contacted respectively by opposite end portions of said armature when said armature is tilted about said transverse axis.

5. A relay comprising:

an electrical coil;

means defining one side of an elongated, shallow switching chamber and including a first longitudinally extending magnetic pole element operatively connected to one end of said coil, and

first and second stationary, longitudinally spacedapart, reaction surfaces at least one of which is electrically conductive;

means defining the opposite side of said switching chamher and including a second longitudinally extending magnetic pole element facing said first magnetic pole element and being operatively connected to the opposite end of said coil,

a third reaction surface facing said first reaction surface, and

a fourth reaction surface facing said second reaction surface;

a permanently magnetized, longitudinally elongated armature in said switching chamber having end portions of opposite polarity and being tiltable about a transverse axis located intermediate said end portions between two positions in each of which its respective end portions are adjacent opposite ones of said pole elements; and

a thin springy snapper element connected to the end portions of said armature and including elastically stressed, bi-stable end portions coning angularly away from the ends of the armature in opposite directions and extending respectively into the space between said first and said third reaction surfaces and the space between said second and said fourth reaction surfaces,

longitudinally extending side portions spaced from said armature and connecting said snapper end portions together, and

electrical contact means carried by at least one of said snapper end portions at a location to engage an electrically conductive one of said reaction surfaces.

6. A relay according to claim 5, wherein a pair of transversely spaced apart stationary mounting posts extend into said switching chamber and intersect said transverse axis, wherein said snapper side portions are connected to said mounting posts at the location of said transverse axis, and wherein said snapper element and said armature are connected together only at the end portions of said armature.

7. A relay according to claim 5 wherein the mass of said armature is substantially greater than the mass of said snapper element.

8. A relay according to claim 5 wherein said end portions of said armature include angularly extending front and back faces adapted to be brought into parallelism with the adjacent surfaces of said pole elements upon completion of a tilting movement of said armature between said two positions.

9. A relay according to claim 5 additionally comprising permanent magnet means in said switching chamber for holding said armature in one of the two positions thereof when said coil is unenergized.

10. A relay according to claim 5, wherein said means defining said one side of said switching chamber is in the form of a base plate having contact pins extending therethrough and being insulated therefrom, and wherein said base plate constitutes said first magnetic pole element and the upper ends of said pins constitute said first and second reaction surfaces.

11. A relay according to claim 10 comprising means for mounting said coil above said switching chamber.

References Cited UNITED STATES PATENTS 4/1952 Trainor. 1/1962 Huetten 335-l BERNARD A. GILHEANY, Primary Examiner 7 H. BROOME, Assistant Examiner 

